Turning the bottom of the bowl? Help please

[chitswood]

I have been turning bowls for a few years now, but I cant seem to find a very good way to sand and finish the bottom of the bowl the way I would like to. How is the bottom of the bowl sanded? Is there some tool or technique I dont know?

Also, I have seen signatures on the bottom of bowls, is this just done with a pen? I suspect it was burnt on?:confused: :confused:
Thanks in advance for the help -Darick

[ribot]

Not trying to be smart, but which bottom do you mean? Inside or outside bottom.

[chitswood]

The outside.

[DavidG]

Two ways for a start.
1 -- Finish the bottom before starting on the inside. The whole outside is done first. This leaves a disguised holding point so you need a good chuck to hold the bowl with out leaving much mark.

2 -- As you do now then, when the inside is finished turn the bowl around and hold with either bowl jaws or vacuum chuck (or a jam fit) whilst you finish the bottom.

The writing can be done with a pen (before finish) or burnt on after finish.

[ribot]

What DavidG said.
I usually use the friction fit/jam fit.
The key is to finish before you flip it round.
Whilst on the subject and not trying to highjack the thread, how do you stop the stain which occurs when I use a chuck(nova) to hold the bowl by the base.(black stain where jaws contact wood, usually green/Red gum.)

[DavidG]

(black stain where jaws contact wood, usually green/Red gum.)

Wet wood problem. Use sheet plastic to prevent wet wood to metal contact. Bit of garbage bag.
Also do not close too tight. Just enough to hold.

[Skew ChiDAMN!!]

For bowls where the rim's the widest point, I use a set of home-made cole jaws. When the widest point is within some 30mm of the top of the bowl, I use the same cole jaws with longer door-stop rubbers. In other cases I'll use either a smaller set in expansion mode or a padded jam-chuck that fits inside the bowl along with a dowel in a jacob's chuck for the tailstock.

Other options would be a vacuum chuck, which is fairly simple to make, or a "donut chuck" which is a ring that's attached to the faceplate with threaded rods & wing-nuts, clamping the bowl in-between. I dislike the last: had more failures than successes with 'em.

Personally I like to turn the base last, to remove all signs of the mount and decorate the base... but this can lead to BIG headaches if I have to remount the bowl later for any reason.

[chitswood]

Two ways for a start.
1 -- Finish the bottom before starting on the inside. The whole outside is done first. This leaves a disguised holding point so you need a good chuck to hold the bowl with out leaving much mark.

2 -- As you do now then, when the inside is finished turn the bowl around and hold with either bowl jaws or vacuum chuck (or a jam fit) whilst you finish the bottom.

The writing can be done with a pen (before finish) or burnt on after finish.

I have tried the first choice and it doesn't work too well with the chuck I have, There will be teeth marks no matter what I do.
The other problem is I have heard of something similar to the vacuum chuck, but I have seen none of these chucks and don't know how to get one. Thanks -Darick

[Skew ChiDAMN!!]

Cole jaws are simple to make... this 'un just uses door-stoppers mounted upside-down. Although 'tis made from MDF, I really don't recommend it... ply is far, far better. I just didn't have any to hand when I knocked it together. [shrug] In this 'un the door-stoppers are just screwed into the MDF at the appropriate position, but normally I'd drill through and use small bolts & wing-nuts.

[Hickory]

There are a number of different ways to turn the bottoms, There is the cole jaws as previously discribed, There is a vacuum chuck that holds the plate or bowl and a rig jig that holds the bowl between two discs with on having the center cut out to expose the bottom, Here is a link to a fellow's discription of how to make one.

http://www.enter.net/~ultradad/bowljig.html

As for the signature: I use an Extra fine Sharpie (felt tip pen) After several coats of finish but before the last coat, I write my name & date. Not on raw wood as it will bleed and make a fuzzy image. I use Wipe-on Polyurethane a great deal and I find that after a few coats, I scuff the bottom and Sign, then add one more coat.

[chitswood]

thanks everyone, this is real helpful.

[Cliff Rogers]

..., Here is a link to a fellow's discription of how to make one.

http://www.enter.net/~ultradad/bowljig.html

....

Similar jig described on page 60 of the March issue of Woodturning mag.
The author used it to turn a 'triplet' of bowls in the one piece of fence post.

[TTIT]

My preferred method is the Longworth chuck - like 'em so much I made two! Trick is to make them so they fit on to your normal chuck/jaws so theres no need to muck around swapping chucks. I've made mine from perspex but the originals were made from ply. Very easy to make and very easy to use - worth a shot.

[hughie]

''I've made mine from perspex but the originals were made from ply''

TTIT,
I have a sheet of 6mm polycarbonate that I intend to use for a Longworth chuck. But I see that your chuck looks like its made of thicker stuff. How thick is the material you used?

hughie

[Caveman]

Here's a compression/doughnut chuck I made. Pretty basic - but I find it doesn't allow for the best of access to the bottom of the bowl.

Had not heard of the Longworth chuck - looks great and very friendly to use. Nice pics TTIT - might have to try one of them methinks. Presumambly works just as well in compression mode as opposed to expanding as in the pics???